In recent years, an imaging device which captures information on direction distribution of incident light, that is an imaging device called as “plenoptic camera”, is known.
In optical systems of the plenoptic camera, a compound eye-like lens (hereinafter, referred to as “micro lens array”), in which extremely small lenses (hereinafter, referred to as “micro lenses”) are repeatedly arranged, is inserted between a conventional imaging lens (hereinafter, referred to as “main lens”) and an imaging element.
Each micro lens which forms a micro lens array distributes the light focused by the main lens to a plurality of pixel groups in an imaging element according to the angle of the received light.
That is, if an image focused on an imaging element by each micro lens is hereinafter referred to as “sub-image,” data of image formed by an aggregate of a plurality of sub-images is output from an imaging element as data of a captured image.
Such captured image by the plenoptic camera is hereinafter referred to as “light field image.”
The light field image is generated by the light which is incident through not only a conventional main lens but also the micro lens array. Therefore, the light field image includes two-dimensional spacial information which indicates from which part the light beam reaches and is included in conventional captured images, and further includes two-dimensional direction information indicating a direction from which the light beam reaches when viewed from imaging element, as information not included in conventional captured images.
The plenoptic camera, after imaging the light field image, can reconstruct an image on a plane separated at an arbitrary distance ahead at the time of imaging using the data of the light field image.
In other words, the plenoptic camera can freely make data of an image (hereinafter, referred to as “reconstruction image”) by using data of light field image after the imaging as if the image is focused at predetermined distance and captured, even if the light field image is captured without focusing at predetermined distance.